The problems of obesity and insulin resistance have been linked to type 2 diabetes. Diabetes is on the rise and fully effective treatments are lacking. In the spectrum from obesity and insulin resistance, to diabetes, profound metabolic dysfunction is linked to increased risk for cardiovascular disease. In this Program Project, our goal is to uncover fundamental mechanisms by which macrophage inflammation impacts metabolic dysfunction in diabetic atherosclerosis and obesity. Published and preliminary data reveal that in high fat feeding and obesity in human subjects and in mice, ligands of the receptor for AGE (RAGE) are increased in adipose tissue and other key metabolic tissues, even in the absence of diabetes. Our data reveal that genetic deletion of Ager (gene encoding RAGE) results in significant protection against high fat feeding induced obesity and insulin resistance. Importantly, the accumulation and inflammatory polarization of adipose tissue macrophages are greatly reduced by deletion of Ager. Project 3 will address the hypothesis that RAGE/DIAPH1 regulates obesity, adiposity and metabolic dysfunction in high fat feeding, both via cell autonomous mechanisms, and via macrophage cross-talk with the adipocyte. Our Project will explore four key properties of macrophage inflammation to discover RAGE-dependent mechanisms in high fat feeding: monocyte recruitment; macrophage retention and egress; polarization; and metabolic regulation. Project 3 will work closely with Projects 1 and 2 to address the common vs. distinct mechanisms of macrophage inflammation in diabetic atherosclerosis and in obesity. Project 3 will work closely with Project 1 to test novel small molecule antagonists of RAGE/DIAPH1 interaction in atherosclerosis and in high fat feeding, and will work closely with Project 2 to discern common vs. distinct mechanisms by which RAGE/DIAPH1 contribute to regulation of NETRIN1/UNC5B and metabolic dysfunction in macrophages in high fat feeding. Project 3 will utilize all three Cores of the Program over all five years.